1. Field of the Invention
This invention belongs to the field of seed coating compositions containing a pesticide and, more particularly, to such compositions containing a pesticidal carbamate as the active ingredient.
2. Description of the Prior Art
Carbamates of dihydrobenzofuranols (U.S. Pat. Nos. 3,356,690 to Orwoll; 3,474,170 to Scharpf; and, 3,474,171 to Scharpf) of which carbofuran is a well-known commercially available representative (FMC Corporation's Furadan) are pesticide substances effective against a wide variety of crop-destroying insects, nematodes, etc., whether applied to soil or to the above ground parts of growing plants. The carbamates are generally formulated with other compatible materials such as particulate carriers, wetting agents, dispersants, and the like, which facilitate their use. However, direct contact of carbofuran and other carbamate pesticides is known to cause severe damage to some types of seed.
U.S. Pat. No. 3,545,129 to Schreiber describes a multiple coating for seed having (a) an inner coating which is permeable to water, (b) an intermediate coating which is semipermeable to water, and (c) an outer coating which is substantially impermeable to moisture but is fissionable at frost temperatures. The inner coating contains a coating material such as powdered charcoal, a binder and a plasticizer. Nothing is said in this patent regarding the use of a non-alkaline powdered charcoal.
It is known from the literature relating to the agricultural use of activated charcoal (viz. Linscott, et al., Weeds, 15 (1967), pp. 304-306; Andersen, Weed Res., 8 (1968), pp. 58-60; Andersen, Weed Res., 9 (1969), pp. 254-257; and, Moyer, et al., Soil Biol. Biochem., Pergamon Press (1972), Vol. 4, pp. 307-311) that charcoal, or amorphous carbon applied to soil or furrow, protects seeds from injury due to various pesticides.
Heretofore, there has been no recognition or appreciation that charcoals such as alkaline Norit (American Norit Co., Inc.) can significantly counteract the effectiveness of the carbamate family of pesticides.